1. Field of the Invention
This invention relates to a photographic material comprising a film support of a polymer comprising substantially a polymer of styrene and having thereon a subbing layer which has strong adhesivity to a photographic layer comprising a hydrophilic resin binder, such as light-sensitive layers or image-receiving layers as are used in conventional photography.
2. Description of the Prior Art
Generally a polymeric film consisting mainly of styrene is a desirable material for a photographic support because of its excellent transparency, physical strength, dimensional stability and strength. However, such a support has a very hydrophobic surface, as is apparent from the molecular structure, so some pretreatment such as undercoating is necessary to provide a photographic layer consisting of a hydrophilic resin binder on the support with strong adhesion such that the photgraphic layer does not separate from the support during processing and using.
As a method of undercoating a photographic support consisting substantially of a styrene polymer, it is known to use homopolymers or copolymers of acrylic acid esters, methacrylic acid esters, acrylic acid, methacrylic acid and acrylamide, or copolymers thereof with styrene.
However, a one layer coating of the above-mentioned (co)polymers on the support is insufficient to obtain effective results and, therefore, complicated multi-layer undercoating has been carried out in practice. For example, undercoating using a three layer structure is most commonly conducted wherein a polymer layer of the above-mentioned acrylic type is provided as a first layer, a nitrocellulose layer is used as a second layer and further a dispersion of gelatin in an organic solvent is employed as a third layer. Such multi-layer undercoating is most undesirable because of the required complicated processing, the increase in the production cost and the deterioration in the stability of a product. Furthermore, this method is dangerous because it is necessary to use a very flammable nitrocellulose resin.
U.S. Pat. No. 3,072,482 Beeber et al discloses vinyl methyl ether-maleic anhydride polymer used in a small amount in a subbing layer as a supplementary component of the subbing layer where a gelatin subbing solution (cf. Col. 2) is necessary.
U.S. Pat. No. 3,645,740 Nishio et al and U.S. Pat. No. 3,770,443 Osada et al disclose photographic elements which contain epoxy compounds useful in the present invention.
U.S. Pat. No. 3,527,605 Fisch et al discloses epoxidized materials useful in a subbing layer.
As a result of research on suitable undercoating materials for the purpose of overcoming the above-described disadvantages, it has been found that a complete or partial reaction product of a copolymer of styrene or vinyl acetate with maleic anhydride with water or a hydroxy compound represented by the general formula R.sub.1 --OH, wherein R.sub.1 is a monovalent hydrocarbon group having 1 to 12 carbon atoms or monovalent organic group having 2 to 12 carbon atoms and consisting of at least two hydrocarbon fragments and at least one ether linkage between said hydrocarbon fragments (R.sub.1 does not represent cyclic ether linkage), preferably an alkyl group, is very effective for the adhesion of a hydrophilic photographic layer to a support of a polymer consisting predeominantly of styrene. The above-described copolymer has in its polymeric structure, at least partially, recurring units having the formula: ##STR1## in which R.sub.3 is a hydrogen atom or a group described above for R.sub.1 and R.sub.2 is a phenyl group (when the copolymer is a styrene copolymer) or a --OCOCH.sub.3 group (when the copolymer is a vinyl acetate copolymer).
When a support of a polymer consisting mainly of styrene is undercoated with the above-described copolymer, the adhesiveness of a hydrophilic photographic layer to this support is markedly increased, but the undercoated layer must be quite thick. i.e., a thickness of more than several microns. Accordingly, coating and surface difficulties often take place. Furthermore, the adhesive strength is not quite as sufficient as desired, in particular, when wetted in a strongly alkaline developer.